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Molecular cloning of a membrane bound tyrosine-specific protein kinase from rat spleen
Abstract:
Tyrosine-specific protein phosphorylation is believed to play an important (though poorly understood) role in various cellular functions in many normal and malignant cells. In order to understand the function of tyrosine-specific protein kinases in normal cells, it is necessary, as an initial step, to identify genes (and proteins) for these enzymes. For this purpose cDNA libraries were constructed in plasmid vector pGEM-3Z and lambda gt11 using mRNA from rat spleen. From these cDNA libraries, cDNA clones coding for a src-related tyrosine-specific protein kinase were isolated. The largest clone (L115) was 1.94 kb in size. Various restriction fragments of this clone were subcloned in plasmid vector for sequencing. The complete nucleotide sequence of the largest clone showed an open reading frame coding for a protein of 503 amino acids. The presence of a glycine at position 2 and an arginine at position 7 indicated that this protein is likely to be acylated at glycine 2 and therefore associated with plasma membrane. This gene showed high homology to human and mouse hck and hence it is perhaps the rat homologue of hck. Moderate level of expression of this gene was observed only in the adult rat spleen and not in other tissues. These results suggest that this kinase gene is expressed in a tissue specific manner.
Insights
Researchers identified a novel tyrosine-specific protein kinase gene in rat spleen. This gene, potentially a rat homologue of hck, is expressed in a tissue-specific manner, offering insights into normal cellular functions.
Area of Science:
- Molecular Biology
- Biochemistry
- Cellular Biology
Background:
- Tyrosine-specific protein phosphorylation is crucial for cellular functions in normal and malignant cells, but its precise role remains unclear.
- Identifying genes encoding tyrosine-specific protein kinases is essential for understanding their function in normal cells.
Purpose of the Study:
- To identify genes for tyrosine-specific protein kinases in normal rat cells.
- To characterize a novel src-related tyrosine-specific protein kinase gene isolated from rat spleen cDNA libraries.
Main Methods:
- Construction of cDNA libraries in plasmid vector pGEM-3Z and lambda gt11 using rat spleen mRNA.
- Isolation and characterization of cDNA clones encoding a src-related tyrosine-specific protein kinase.
- Sequencing of the largest clone (L115) to determine its nucleotide sequence and predict the encoded protein.
Main Results:
- A cDNA clone (L115) of 1.94 kb was isolated, containing an open reading frame for a 503-amino acid protein.
- The predicted protein sequence suggests potential acylation at glycine 2 and plasma membrane association.
- The gene exhibits high homology to human and mouse hck, suggesting it is the rat homologue of hck.
- Moderate expression of this gene was detected exclusively in adult rat spleen, indicating tissue-specific expression.
Conclusions:
- A novel tyrosine-specific protein kinase gene, likely the rat hck homologue, has been identified and characterized.
- The tissue-specific expression pattern in adult rat spleen suggests a specialized role in this tissue.
- Further research into this kinase could elucidate its function in normal cellular processes and potential involvement in diseases.